Cash, Cash Equivalents And Marketable Securities (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Transfers into Level 2	$ 0		$ 0
Transfers out of Level 2	0		0
Proceeds from sales of available-for-sale securities	14,386,000	3,883,000	16,650,000	10,255,000
Gross gains or losses related to sales of marketable securities	0	0	0	0
Net unrealized losses included in accumulated other comprehensive income, before taxes	43,000	27,000	31,000	22,000
Contractual maturities of marketable securities within 1 year	9,519,000		9,519,000
Contractual maturities of marketable securities, years 2-5	17,599,000		17,599,000
Contractual maturities of marketable securities, years 6-10	5,263,000		5,263,000
Contractual maturities of marketable securities, after 10 years	12,675,000		12,675,000
Marketable securities liquidation period			7 days
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification out of AOCI	$ 0	$ 0	$ 0	$ 0